In this step you will mark the major (longer, horizontal line in the PDF file) and minor (shorter, vertical line) axes. These can be erased when you are done with the sundial.
I recommend chalking out the sundial with blackboard chalk, as blackboard chalk can be very easily erased with a wet rag even on quite rough pavement.
The horizontal line (I will talk of "vertical" and "horizontal" with the PDF file held the normal way so that the text faces the way they normally do) needs to run east-west. The vertical line needs to run north-south. Each page on the PDF file has an arrow showing which way north should go.
You will need to find out which direction true geographic (not magnetic) north is. There are three ways of doing that. The first way is the simplest but less precise.
1. Take the last page of your PDF file which shows the completed sundial. Put it on level ground where it is sunlit. Place a pencil upright on the vertical line on your correct date (e.g., if it's August 10, put it in the August area, a little closer to the July end). Check what time it actually is. Rotate the sundial, keeping the pencil in place, until the shadow of the pencil shows the correct time. (See first photo.) The "N" arrow on the page will then point north. (For slightly higher precision, use the time correction chart--see Step 7 for how it works.)
2. Use a magnetic compass, but you must correct for magnetic declination (the geographic north pole is not the same as the magnetic north pole) or your sundial will show the wrong time. Read this Wikipedia article
and follow the links at the bottom of it to find out what the magnetic declination at your location is. If your declination is, say +10° (sometimes shown as "10° E"), true north will be 10 degrees to the west
of your compass's north needle (the "E" in "10° E" means that magnetic north is east of true north); if your declination is -10° (or "10° W"), true north will be 10 degrees to the east
of your compass's north needle.
3. At night, find the north star
, and carefully draw an arrow on the ground aligned with it (e.g., by setting up a telescope or using a quadrant
Also, a helpful hint is that in many cities streets and house walls are aligned along true geographic directions.
Once you know which way is north, draw a center point for the two axes, and then draw axes outward from the center point (towards the north, south, east and west), using the dimensions shown on Step 2 of the PDF file. Make sure the two axes meet at right angles. I used a piece of shelving I had in the garage for making things be at right angles(photo 2).Hint:
If you can find a joint between paving stones that runs exactly east-west, using that for your east west line will make drawing the ellipse a lot easier. In this case, you don't need to draw the horizontal line at all, but you do need to measure off and mark its center and endpoints. If the joint has significant width (more than about an 1/8" or 0.5cm), you will need to decide which edge of the joint counts as your official line, and do all your up/down measurements from that.